1. Field of the Invention
The object of the present invention is a method of managing a secure terminal also referred to as a reader, and a security circuit for implementing the method. It relates to the field of so-called smart microcircuit cards and more generally the field of portable smart objects. This field is the one by which, with electronic circuits, either carriers of smart cards are authenticated, or information contents contained by the memories of these cards are authenticated, or finally payments, or credit increases, are carried out by modifying a number stored in the card and representing payment units or loyalty points.
The object of the invention, in view of the very considerable development of transactions accessible with smart cards, is to make the read terminals, the available number of which is growing in parallel with the uses of smart cards, safer, to make them secure.
2. Related Background
A method of managing transactions using smart cards is for example described in European patent application EP-A-91 400 201.9 filed on Jan. 29, 1991.
The security systems in use at present have, in the readers, security circuits whose task is notably to control the execution of all these verification or authentication protocols executable by the reader. These security circuits, referred to as SAM (SECURE APPLICATION MICROMODULE) circuits, are generally removable and are connected to the reader in order on the one hand to provide this security operation control, and on the other hand to specify certain operations related to a particular application implemented by the reader. An application is a series of operations executed by a reader, or a device to which this reader is connected, and which leads to the satisfying of a requirement (in terms of goods or services) expressed by the carrier of the card. The removable nature of these security circuits makes them insecure as regards defrauders who are suspected of wishing to know the secret thereof. This will be even more achievable as the number of security circuits becomes large.
One aim of the invention is to guarantee that the terminals and the security modules are not used outside the application to which they are dedicated. This is because the illegal use of a security circuit, without a terminal, is critical from the security point of view since it is possible for a defrauder to have information on the secrets contained in the security circuit. The use of a terminal without its security circuit is generally of no interest since the terminal does not hold the secrets of the application. It is therefore not capable of doing much. The use of a terminal and its security circuit is furthermore in certain cases also critical. This is because the terminal plus security circuit assembly makes it possible to carry out complete operations on real cards. It is therefore essential to restrict the use of security circuits alone and security circuit plus terminal assemblies.